1. Field of the Invention
Methods consistent with the present invention relate to transmitting data using authentication between a first device and a second device.
2. Description of the Related Art
A digital transmission content protection (DTCP) of the Digital Transmission Licensing Administrator (DTLA) (http://www.dtcp.com/) was first developed as a protocol for protecting audio/video (AV) data transmitted between devices based on the Institute of Electrical and Electronics Engineers (IEEE) 1394 standard. The DTCP has since been expanded to support standards for universal serial bus (USB), Media Oriented Systems Transport (MOST), Bluetooth, and Internet protocol (IP). In general, a method of transmitting compressed AV data can be used for any type of data, regardless of the purpose of the transmission or the content format.
Recently, there have been increasing demands for transmitting and receiving uncompressed AV data via a wireless transceiving system having a transmission rate of several Gbps, using the tens of GHz band (for example, 4 Gbps at 60 GHz), and thus research into this field has been very active.
DTCP can be applied to this field, and here, an encrypting algorithm must be very fast, since a large amount of data is transmitted. Also, when DTCP is applied to an 802.11 wireless LAN environment, wired equivalent privacy (WEP), which is a method of protecting data in the 802.11 standard, or a corresponding method of protecting data, such as Wi-Fi protected access (WPA) or WPA2, should be used before authenticating DTCP or transmitting content protected by DTCP.
WEP is a method of transmitting and receiving encrypted data between a client and an access point in an 802.11 wireless LAN.
WEP has a prior condition that the client and the access point share the same key. A method of generating the shared key is not mentioned in WEP, but may be directly input by a user. In other words, a user may input an intrinsic identification number of the access point to the client, such as a personal computer (PC). When the shared key is generated, the access point and the PC transmit and receive encrypted data using the shared key.
An encrypting method using WEP includes performing authentication between devices and authentication of message content.
The shared key in WEP is used for authenticating devices which transmit/receive data. Upon receiving a random number from the access point, the client encodes the random number and responds to the access point. Then, the access point decrypts the encrypted random number and checks whether the result of decrypting is equal to the original random number. Accordingly, it is determined that the client has the shared key. Only then can data be transmitted and received.
Also, WEP includes authenticating a message. To detect if a third party intercepts and changes the message, a cyclic redundancy check (CRC) bit in each 32 bits can be encrypted and transmitted.
According to a related art technology, data is protected and transmitted using WEP during DTCP communication. However, encrypting data using both DTCP and WEP is very inefficient, in a DTCP communication method having a transmission rate of several Gbps.